Micronutrient Gaps Most American Adults Don't Know They Have

Vitamin D is arguably the most widespread micronutrient gap in the United States. National Health and Nutrition Examination Survey (NHANES) data has repeatedly shown that a significant portion of Americans have blood levels below what is considered sufficient. The body can produce vitamin D through sun exposure, but factors like indoor lifestyles, sunscreen use, darker skin tones, and living at northern latitudes reduce synthesis considerably.

Dietary sources are limited but meaningful: fatty fish such as salmon and mackerel, egg yolks, and fortified foods like milk, orange juice, and breakfast cereals are among the best options. People with very limited sun exposure, older adults, and those with darker skin tones are at particular risk and may benefit from discussing their levels with a clinician.

Calcium is critical for bone density, muscle function, and nerve signaling. While dairy products are the most familiar source, intake has declined as many Americans have moved away from milk and yogurt without replacing them with adequate alternatives. Adults over 50 face the highest risk of low intake, as calcium needs increase with age while absorption efficiency decreases.

Good food sources include dairy products, calcium-set tofu, canned fish with soft bones (like sardines and canned salmon), fortified plant-based milks, white beans, and cooked leafy greens such as bok choy and kale. Note that spinach, though nutritious, contains oxalates that reduce calcium absorption.

Potassium is essential for healthy blood pressure, fluid balance, and muscle contraction. It is one of the nutrients most consistently under-consumed across all adult age groups in the U.S., largely because the best sources — fruits, vegetables, beans, and whole grains — are eaten in insufficient quantities in typical American diets.

Bananas get most of the attention, but potassium is actually abundant in white potatoes, sweet potatoes, avocado, lentils, plain yogurt, and leafy greens. Increasing vegetable and legume intake is one of the most effective strategies for closing this gap.

Magnesium participates in hundreds of enzymatic reactions in the body, including those involved in energy production, protein synthesis, and blood sugar regulation. Despite its widespread importance, surveys consistently show that a large share of American adults do not meet the Estimated Average Requirement.

Magnesium is concentrated in foods that tend to be under-represented in typical diets: pumpkin seeds, chia seeds, almonds, black beans, edamame, whole wheat bread, and dark leafy greens. Highly processed diets, which rely on refined grains stripped of their outer layers, contribute to this shortfall.

Vitamin A supports vision, immune function, and cell growth. The U.S. diet provides two forms: preformed vitamin A from animal foods (liver, dairy, eggs) and provitamin A carotenoids from plant foods, primarily beta-carotene. The conversion of beta-carotene to active vitamin A is less efficient than it was once assumed, which means many people consuming mostly plant-based sources may still come up short.

Rich sources include beef liver (in modest amounts), dairy products, eggs, orange and yellow vegetables like carrots and sweet potatoes, and dark leafy greens such as spinach and kale. Pairing plant-based sources with a small amount of fat improves carotenoid absorption.

Vitamin E functions primarily as an antioxidant and plays a role in immune function and skin health. It is one of the four nutrients formally identified as under-consumed by the Dietary Guidelines for Americans. Low intake is largely tied to the limited consumption of nuts, seeds, and vegetable oils — foods that Americans often reduce when trying to cut fat from their diets.

Sunflower seeds, almonds, sunflower oil, wheat germ oil, peanuts, and spinach are among the best food sources. For a look at how trace minerals with similarly overlooked status fit into the picture, see our piece on zinc, selenium, and iodine.